1. Field of the Invention
This invention relates to the field of grouped container handling, for example in bottling plants. In particular the invention provides an improvement in handling systems intended to process a plurality of containers while the containers are arranged in an X-Y array in alignment with operative elements of the handling system. The array of operative elements can be, for example, an X-Y array of nozzles of a ballast loader, container filling machine, cleaning apparatus or the like, a filling or capping apparatus having a plurality of stationary or movable heads, or other stationary or movably arranged devices which operate on containers expected to be located at predetermined positions in an array. The invention provides an apparatus for engaging the periphery of an X-Y array of containers so as to force them into a regular array notwithstanding gaps in the array.
2. Prior Art
Most container processing techniques require that the containers be positioned serially in line, where they are engaged by devices which clean, fill and seal the containers. The containers generally are converted from a bulk storage configuration to a serial line for processing. For example, a serial line of containers can be fed through a carousel-type filling machine having a number of heads which individually engage single containers and fill them as the containers move around the carousel.
In a conventional bottling system, empty containers are supplied on pallets wherein containers are stacked in an X-Y array over one another with interleaved panels supporting each level or rank on the lower level(s). A depalletizer receives the pallet and raises the pallet until the topmost level or rank of containers is coplanar with a receiving platform. The rank of containers is then pushed laterally onto the receiving platform.
Where the containers are to be converted to a serial line as described, the receiving platform leads to a funnel-like path wherein successive decreases in width force the containers into single file, from which the containers proceed one after another through continuously operating processing steps. This funnel-like section serves to accumulate the containers because each rank from the depalletizer requires a certain time to be converted from an X-Y array of containers to a single file, and theoretically, the next rank is supplied just as the previous rank is exhausted.
The containers in the single file are then carried by a conveyor typically having one or more endless loops of conveyor belt, horizontally attached link plates, or rollers, which define a moving horizontal platform for supporting the containers while advancing the containers to the next processing station. Each container simply rests on a horizontal surface which is moved to advance the container.
The bottling system preferably runs continuously. For maximum production it is necessary to avoid both stoppages of the line and gaps in the single file progression of containers. In addition to the lost production caused by gaps in the line, the containers to some extent support one another upright as they are moved along the conveyor. Where gaps occur, the containers leading and trailing the gap lack support from adjacent containers and more easily fall over. When a container falls over, the entire line may become jammed. This is a particular problem with lightweight plastic containers such as polyethylene terephthalate (PET) containers. These plastic containers are thin, light and durable, which are obvious advantages in reduction of shipping weight, ability to use lighter production equipment and the like. However, the containers are so lightweight as to be unstable when carried on a horizontal conveyor surface.
In order to avoid jamming of bottling lines when running lightweight plastic containers, the lines are run substantially more slowly than a comparable line running glass containers, which are heavier and therefore more stable. Even at slower rates of throughput, the plastic containers tend to fall over much more frequently than do glass containers, and more workers are needed to correct recurrent jamming and resume proper operation of the line. The plastic containers are so lightweight that minor breezes in the plant, e.g., due to opening of an exterior door, can cause disruptive fallovers.
Plastic containers are used for a wide variety of products. Standard container capacities, for example for beverage containers, are 16 ounce, 20 ounce, 1 liter and 2 liter. Of course other sizes are also possible and in standard use for various products. The containers vary not only in size but also in shape. The containers can be cylindrical or tapered, round, square or oval in cross section. Some forms of plastic containers are relatively tall and thus are easily knocked over by uneven conveyor passages, impacts, or by breezes in the bottling plant.
Plastic containers have been made with an excess of plastic at the bottom, which helps to preclude fallover. A "petaloid" form of container has a scalloped bottom with radially oriented folds which increase the rigidity of the container at the bottom and also provide additional weight at the bottom due to the additional material at the fold. Another form of container is the "champagne" type, which has an inward dome in the bottom. Some containers are supplied with an outer reinforcing cup that is bonded to the outside of the container at the bottom. The reinforcing cup is generally made of less expensive plastic than PET, is opaque rather than clear, and defines a bottom weight that makes the empty container more stable when placed on its bottom. The reinforcing cup, however, conceals the content at the bottom, requires additional manufacturing steps, and renders the container unacceptable for recycling into new PET material. Plastic containers are not recycled by cleaning and re-use as are glass containers. Instead, they are shredded and the material is molded into new containers or other products.
According to one method intended to reduce fallovers, plastic containers are not carried solely on horizontal support surfaces, but instead (or in addition) are carried by a structure having rails or flanges that face inwardly near the neck of the container. The containers are provided with a circumferential bead or flange at the neck, that rests on the conveyor rails to support the container. In an embodiment known as an Airveyor, the containers are supported entirely by the rails, and blasts of air are used to propel the containers along the conveyor path. While such systems are useful, it is desirable to provide a handling arrangement that does not require added container material, processing requirements and/or conveyor structure.
For handling lightweight containers at increased production speeds in processes such as bottling plants, U.S. Pat. No. 5,159,960 discloses a ballast loading system which renders lightweight containers more stable temporarily, without increasing the cost of container production and materials, and which permits the containers to be run as fast as stable glass containers on simple horizontal supporting conveyors. This is accomplished by adding a limited quantity of water or other ballast, rendering the containers bottom-heavy and stable, at least from a depalletizing step to a cleaning operation at which the ballast is emptied.
Empty containers from the depalletizer are arranged in an upright orientation and in an X-Y array. The array is positioned below a dispenser having an X-Y array of nozzles coupled to a supply of ballast such as a tank of water coupled in common to all the nozzles. A limited quantity of ballast is dispensed into the containers by momentary operation of the nozzles, or alternatively the containers move through a spray which generally encompasses the containers, the latter producing overspray which must be collected. Having been loaded with a limited quantity of ballast, e.g., as little as three to ten percent of the container volume, or less, the containers are stable and can be moved along a conveyor for further processing. The ballast is preferably water and can be removed after the containers have been moved on the conveyor, for example by inverting the containers to drain the ballast by gravity. In a bottling plant the typical rinsing apparatus can be used to empty the containers of ballast in this manner. This arrangement works quite well with polyethylene terephthalate (PET) containers, and precludes many of the problems of container fallover and container jamming that are associated with very lightweight containers.
It is desirable in a ballast loader having an array of nozzles to operate the nozzles only when the containers are in place to be filled, so as to avoid the need to collect dispensed ballast material which misses the openings at the top of the containers. The containers can be moved in an array to the nozzles, whereupon a photocell, limit switch or other sensor triggers momentary operation of the ballast dispenser. The nozzles emit into the containers which are in place, but may miss or only partly fill containers which are at least slightly out of position.
Typically, in advancing an X-Y array of containers, a sweep bar urges the containers forward from behind the array. Assuming some resistance, containers having a round cross section nest against one another in an alternating pattern. Frequently, however, the array of containers which is nested in this manner has voids. In a gang dispensing machine which is not assured of accurately and exclusively dispensing into correctly positioned containers, and which emits water ballast, the result is simply excess water to be collected. In a filling machine for material contents to be loaded into containers, the problem is more serious.
It is possible to ensure that containers are in correct position by defining parallel paths for the containers using guide structures which force the containers into a number of single files. Such a structure is expensive and increases the tendency of containers to fall over, especially when being forced into the serial paths.
U.S. Pat. No. 4,055,202--Greene discloses a gang filling machine intended to operate on an X-Y array of containers, in this case to load the containers with their ultimate contents. In order to ensure that the containers occupy correct positions in the X-Y array, the containers are held in a compartmented case defining correct X-Y positions for each container. It is unclear how the containers are loaded into the compartmented case, and presumably the containers are loaded individually, being dropped along their longitudinal axes into the compartments. In order to ensure that the filling machine does not emit contents into an unoccupied position, the filling machine has valves operable to open by contact with the containers or to remain closed when no container is encountered. This arrangement avoids the dual problems of correct positioning and gapping of array locations. In order to address these problems, however, a relatively complicated machine is required which incorporates selectively operable valves, relative axial movement of the containers into the compartments, axial movement of the valves over a substantial length of stroke, and a structure with separate compartments for individual positioning of each container.
It would be desirable in a gang filling machine such as a ballast dispenser or content filling machine to ensure that the containers occupy the desired positions without placing the containers in individual receptacles, which is cumbersome. It would also be desirable to enable selective operation of valves using a relatively shorter stroke, i.e., which need not include sufficient displacement along the stroke to engage the outer surface of the container.
According to the invention, an array of containers is engaged from the outside via one or more contact bars which includes scallops operable to engage and correctly position the containers along a periphery of the array. Means are provided to urge the scalloped contact bar toward the array. The peripheral containers are thus forcibly aligned to the scallops. Advancing the contact bar extends the alignment of the containers inwardly toward the middle of the array, as the aligned peripheral rows and/or columns engage and align the next inward row and/or column, proceeding inwardly. At a sufficient advance, the containers are arranged in direct contiguous contact throughout the array. Based on the looseness of the original spacing of the containers, there is a possibility that the array may include voids. However, the containers which are engaged in this manner substantially all occupy correct array positions.
The invention is quite apt for a ballast filling machine having an array of ballast dispensing nozzles. The nozzles can be operated momentarily, with a minimal loss of misdirected ballast material, i.e., lost ballast material being limited to the voids. The invention is also apt for a gang filling machine comprising selectively operable valves. Unlike Greene, where X-Y positioning is provided using relative displacement along the container axes of the containers, the means defining their compartments and/or the selectively operable valves, the invention enables valve operation along a very short stroke.